This invention relates to the preparation of food products of reduced allergenicity.
It is known that allergies to cows' milk and to the milks containing cows' milk adapted to the needs of infants are due to the fact that the whey proteins of cows' milk differ from the proteins of mother's milk and can constitute allergens. Among the latter, the principal recognized allergens are, primarily, alpha-lactalbumin (aLA) and beta-lactolglobulin (bLG) and, to a lesser extent, the immunoglobulins (particularly IgG) and serum albumin (BSA).
Attempts have been made to eliminate their allergenicity by converting them into peptides by hydrolysis.
According to U.S. Pat. No. 4,293,571, a protein hydrolyzate is prepared by pancreatic hydrolysis, the non-hydrolyzed proteins are coagulated by a heat treatment, the hydrolyzate is then subjected to ultrafiltration to eliminate the coagulated residual proteins and the macropeptides which could constitute allergens.
It has also been proposed, cf. for example, in Blatt et al, Anal. Biochem. 22: 161-165, or in European patent application No. 22 019, directly to hydrolyze whey proteins in an ultra-filtration plant and to collect the peptides as they are formed. In a membrane reactor of the type in question, the non-hydrolyzed proteins remain in the retentate which is recycled to the hydrolysis compartment to be re-hydrolyzed. It would appear that, even under these conditions, it is not possible in practice completely to hydrolyze all the whey proteins. The serum albumin, for example, accumulates in the hydrolysis reactor. The various species of immunoglobulins are also resistant to hydrolysis by the pancreatic enzymes and are only partially split. The large fragments or macropeptides obtained by hydrolysis of the immunoglobulin of bovine colostrum (IgG) using trypsin or papain largely retain the allergenicity of IgG.
In conclusion, it is accepted that it is not sufficient to degrade aLA and bLG because BSA and IgG constitute allergens for human beings and have been described as such. With known methods of physical separation, the minor proteins of high nutritional value are lost.